Vehicle muffler

ABSTRACT

A muffler includes three or more concentric pipes which convey exhaust gases from an input end of the muffler to an output end of the muffler. The exhaust gases reverse direction as they pass from a first pipe into a second pipe, and again as they pass from the second pipe into the third pipe. After the exhaust gases have reversed direction twice, they exit the muffler. Perforated portions of the three concentric pipes can be used to allow exhaust gases to pass from one pipe into another.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to mufflers which are used to reduce sound levels. Such mufflers can be used on internal combustion engines, and with other devices which produce exhaust gases.

2. Background of the Related Art

Internal combustion engines used in vehicles and in other applications typically employ some type of a muffler device to deaden the sound of the exhaust gases exiting the external combustion engine. In a typical muffler, baffles are arranged in the interior of the muffler to force the exhaust gases to reverse direction one or more times before they exit the muffler. However, forming a muffler with multiple baffles requires a significant amount of physical space. As a result, it is difficult to construct an effective muffler which can be used in applications which require a very small muffler volume, such as on motorcycles.

SUMMARY OF THE INVENTION

An object of the invention is to solve at least the above problems and/or disadvantages and to provide at least the advantages described hereinafter.

In a muffler embodying the invention, three or more concentric pipes are connected together. Portions of the smallest diameter and the intermediate diameter pipes are solid walled, and portions have perforations. The perforated sections of the pipes allow exhaust gases to pass from one pipe to another. As the exhaust gas moves from a first pipe into a second pipe, the exhaust gas is forced to reverse its flow direction. By providing three or more concentric pipes, the muffler can cause the exhaust gases to reverse direction at least twice before exiting the muffler.

In some embodiments of the invention, more than five pipes could be used to form the muffler. In addition, the concentric pipes could have any cross-sectional shape including circular, oval, rectangular, or other shapes.

In other embodiments of the invention, the perforated portions of the pipes could be completely eliminated such that gases flowing out of one pipe simply reverse direction and flow into the other pipe.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in detail with reference to the following drawings, in which like reference numerals refer to like elements, and wherein:

FIG. 1 is a perspective view of a muffler embodying the invention;

FIG. 2 is a longitudinal cross-sectional view of a muffler embodying the invention;

FIG. 3 is a cross-sectional view of a muffler embodying the invention taken along section line III-III in FIG. 1;

FIG. 4 is a cross-sectional view of a muffler embodying the invention taken along section line IV-IV in FIG. 1;

FIG. 5 is a cross-sectional view of a pipe which can be used in a muffler embodying the invention;

FIG. 6 is a cross-sectional view of another muffler embodying the invention; and

FIGS. 7 a-7 d are cross-sectional views of mufflers embodying the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A perspective view of a muffler embodying the invention is shown in FIG. 1. As shown therein, the muffler includes three concentric pipes connected together. The smallest diameter pipe 30 can serve as either an input or an output end of the muffler. The largest diameter pipe 20 can serve as the other of the input and output ends of the muffler. An intermediate diameter pipe 40 is located between the smallest diameter pipe 30 and largest diameter pipe 20.

A longitudinal cross-sectional view of the muffler shown in FIG. 1 appears in FIG. 2. In this embodiment, the smallest diameter pipe 30 acts as an input end of the muffler. The right side of the smallest diameter pipe 30 has a plurality of perforations. The perforated section 32 of the smallest diameter pipe 30 allows exhaust gas entering the muffler to flow from the first pipe into the intermediate diameter pipe 40. The right ends of both the smallest diameter pipe 30 and the intermediate diameter pipe 42 are closed off. As a result, exhaust gas flowing into the muffler inside the smallest diameter pipe 30 is forced to reverse its flow direction as it flows from inside the smallest diameter pipe 30 into the intermediate diameter pipe 42. This reversal of the flow direction is shown by the arrows appearing in FIG. 2.

The left side of the intermediate diameter pipe 42 is also perforated. The perforated section 44 of the intermediate diameter pipe 40 allows exhaust gases to pass from within the intermediate diameter pipe 42 into the largest diameter pipe 20. In passing from inside the intermediate diameter pipe 42 to the largest diameter pipe 20, the exhaust gases must again reverse their flow direction. The reversal of the flow direction is also depicted by the arrows appearing in FIG. 2. The exhaust gas then passes down the length of the largest diameter pipe 20 and outside the muffler at the outlet end on the right side of the muffler.

FIG. 3 is a cross-sectional view of the muffler shown in FIGS. 1 and 2 taken along section line III-III in FIG. 1. As shown therein, on the left side of the muffler, the smallest diameter pipe 30 has a solid wall, as does the largest diameter pipe 20. However, the intermediate diameter pipe 40 is perforated at this location.

FIG. 4 shows a cross-sectional view of the muffler of FIGS. 1 and 2 taken along section line IV-IV in FIG. 1. As shown therein, at this location on the muffler, the smallest diameter pipe 30 is perforated, while the intermediate diameter pipe 40 and the largest diameter pipe 20 are solid walled.

A round, flat piece of metal 52 closes off the right ends of the smallest diameter pipe 30 and the intermediate diameter pipe 40. As shown in FIG. 4, small tabs 50 can be used to attach the circular end plate, or the intermediate diameter pipe 40 to the largest diameter pipe 20. This serves to keep the smallest and intermediate diameter pipes centered within the largest diameter pipe 20.

A torus shaped plate 54 is attached to the left ends of the intermediate diameter pipe 40 and the largest diameter pipe 20 to seal off the left ends of these two pipes. The smallest diameter pipe 30 would pass through the torus plate 54.

In the embodiments shown in FIGS. 1-4, the smallest and intermediate diameter pipes have a portion of their length perforated. The remaining portions are solid walled. In alternate embodiments, each of these pipes could be constructed from two separate pieces of pipe having the same diameter that are joined together at their ends, one piece being solid and the other perforated. In still other embodiments, each pipe could be formed of two separate pipes having slightly different diameters. As shown in FIG. 5, a first solid walled pipe 60 could be located inside a perforated pipe 70. The solid walled pipe would be shorter than the perforated pipe 70, such that a portion of the perforated pipe 70 extends beyond the solid walled pipe 60. In additional embodiments, although the slightly different diameters could be arranged as shown in FIG. 5, the larger diameter pipe 70 might be shorter than the solid walled pipe 60, such that only small portions of the two pipes overlap. Also, the perforated pipe could have a smaller diameter than the solid walled pipe, which would reverse the orientation shown in FIG. 5.

In still other embodiments of the invention, the perforated portions of the smallest and intermediate diameter pipes could be completely eliminated. This would mean that the smallest diameter pipe 30 would not extend all the way down to the right side of the muffler, and the intermediate diameter pipe would not extend all the way to the left side of the muffler.

In some embodiments of the invention, as shown in FIG. 6, a fiber filling material 82 can surround the largest diameter pipe of the muffler. A shell 80 can then be formed around the three concentric pipes and the fiber filling material to enclose the muffler. With this type of construction, the largest diameter pipe could be perforated, which would allow some of the gases to pass into the fiber filling material 82.

The fiber filling material 82 can be fiberglass or any other similar material which can be used to dampen sound vibration to further quiet the muffler. In addition, the fiber filling material 82 can be used to help reduce the amount of heat which passes from within the muffler to the exterior shell 80 of the muffler.

Although the above embodiments are illustrated with three circular cross-sections, other cross-sectional shaped pipes could be used. For instance, as shown in FIG. 7 a, all three of the pipes could have an oval cross-section. In addition, mixtures of oval and circular cross-sectional pipes could also be used. For instance, FIG. 7 b shows the smallest diameter pipe 30 and the intermediate diameter pipe 40 having an oval cross-section, whereas the largest diameter pipe 20 has a circular cross-section. FIG. 7 c shows an embodiment of the invention where the smallest diameter pipe 30 and the intermediate diameter pipe 40 have circular cross-sections, while the largest diameter pipe 20 has an oval cross-section. FIG. 7 d shows an embodiment wherein the smallest diameter pipe has a circular cross-section, the intermediate diameter pipe has an oval cross-section, and the largest diameter pipe has a circular cross-section. Of course, any other combination of different cross-sectional shapes could also be used. For instance, the muffler could be constructed using rectangular, square, or other geometric cross-sectional shaped pipes.

In addition, although the embodiments described above show the smallest diameter pipe being used as the input end, and the largest diameter pipe being used as the output end of the muffler, the flow direction of the exhaust gases could be reversed. As a result, each of the arrows shown in FIGS. 2 and 6 could be oriented in the opposite directions so that exhaust gases enter into the largest diameter pipe, reverse direction and pass into the intermediate diameter pipe, and then reverse direction again and pass into the smallest diameter pipe. The smallest diameter pipe would then be used as the output of the muffler.

Furthermore, although the embodiments of the invention illustrated in the drawings comprise three concentric pipes, more than three concentric pipes could be used. For instance, the muffler could be constructed with five concentric pipes which would require the exhaust gases to reverse direction a total of four times before exiting the muffler. In fact, the muffler could have more than five concentric pipes so that the direction of the exhaust gases is reversed multiple times before exiting the muffler.

The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. The description of the present invention is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. 

1. A muffler, comprising: a main body; a first pipe mounted on the body and configured to introduce exhaust gas into the body in a first flow direction; a second pipe mounted on the body such that it at least partially surrounds the first pipe, and such that exhaust gas introduced into the main body via the first pipe is forced to reverse its flow direction as it passes from the first pipe into the second pipe; and a third pipe mounted on the body such that it at least partially surrounds the second pipe, and such that exhaust gas in the second pipe is forced to reverse its flow direction as it passes from the second pipe into the third pipe.
 2. The muffler of claim 1, wherein the first pipe, second pipe and third pipe are all concentric.
 3. The muffler of claim 1, wherein a first portion of the first pipe has a solid wall, and wherein a second portion of the first pipe is perforated such that exhaust gas can escape from the first pipe into the second pipe.
 4. The muffler of claim 3, wherein a first portion of the second pipe has a solid wall, and a second portion of the second pipe is perforated such that exhaust gas can escape from the second pipe into the third pipe.
 5. The muffler of claim 4, wherein the first portion of the first pipe is located adjacent an inlet side of the muffler, and the second portion of the first pipe is located adjacent an outlet side of the muffler.
 6. The muffler of claim 5, wherein the first portion of the second pipe is located adjacent the outlet side of the muffler, and wherein the second portion of the second pipe is located adjacent the inlet side of the muffler.
 7. The muffler of claim 3, wherein ends of the first and second pipes adjacent an outlet side of the muffler are closed.
 8. The muffler of claim 1, wherein the first pipe comprises: a perforated pipe that extends the entire length of the first pipe; and a solid pipe that is concentric with and attached to the perforated pipe, wherein the solid pipe extends only a portion of the total length of the first pipe.
 9. The muffler of claim 8, wherein the solid pipe is located adjacent an inlet side of the muffler.
 10. The muffler of claim 8, wherein the second pipe comprises: a perforated pipe that extends the entire length of the second pipe; and a solid pipe that is concentric with and attached to the perforated pipe, wherein the solid pipe extends only a portion of the total length of the second pipe.
 11. The muffler of claim 10, wherein the solid pipe portion of the first pipe is located adjacent an inlet side of the muffler, and wherein the solid pipe portion of the second pipe is located adjacent an outlet side of the muffler.
 12. The muffler of claim 1, further comprising an outer shell that surrounds the majority of the first, second and third pipes.
 13. The muffler of claim 12, further comprising fiber filling material located between the third pipe and the outer shell, wherein the fiber filling material is configured to dampen sound.
 14. The muffler of claim 13, wherein the fiber filling material comprises fiberglass.
 15. The muffler of claim 13, wherein at least a portion of the third pipe is perforated.
 16. The muffler of claim 1, wherein the first, second and third pipes have a circular cross-section.
 17. The muffler of claim 1, wherein at least one of the first, second and third pipes has an oval cross-section.
 18. The muffler of claim 1, wherein at least one of the first, second and third pipes has a circular cross-section.
 19. A muffler, comprising first, second and third concentric pipes, wherein the smallest diameter pipe is an input pipe, wherein the largest diameter pipe is an output pipe, and wherein exhaust gas entering the muffler is forced to reverse its flow direction as it passes from the first pipe into the second pipe and again as it passes from the second pipe into the third pipe.
 20. The muffler of claim 19, wherein portions of the first and second pipes are perforated, and wherein the exhaust gas passes through the perforated portions to move from one pipe to the next.
 21. A muffler, comprising first, second and third concentric pipes, wherein the largest diameter pipe is an input pipe, wherein the smallest diameter pipe is an output pipe, and wherein exhaust gas entering the muffler is forced to reverse its flow direction as it passes from the first pipe into the second pipe and again as it passes from the second pipe into the third pipe.
 22. The muffler of claim 21, wherein portions of the second and third pipes are perforated, and wherein the exhaust gas passes through the perforated portions to move from one pipe to the next. 